DE102011003622A1 - Flexible multilayered circuit substrate, has flexible film substrates with opposing main surfaces, where bonding material of specific thickness is applied at connecting areas for separating flexible film substrates - Google Patents

Abstract

The substrate (10) has two flexible film substrates with opposing main surfaces whose portions (12) are connected to each other at respective connecting areas (32, 34) by bonding material e.g. adhesive material and solder material, where the connecting areas are disconnected and are separated from the other connecting area at a distance (B0) that is larger than maximum dimension (A0) of the connecting area. The bonding material has specific thickness at the connecting areas for separating the flexible film substrates. The connecting areas are circular, oval or rectangular in shape. An independent claim is also included for a method for producing a flexible multi-layered circuit substrate.

Description

The present invention relates to a flexible multilayer circuit substrate and to a method of manufacturing the same. In particular, the present invention relates to a selective adjustment of the topology of a flexible, multilayer circuit substrate in its manufacture, wherein the multilayer circuit substrate is constructed from a plurality of flexible sheets or film substrates which are disposed by means of a bonding material disposed on separate and specially positioned connection regions , are mechanically connected to obtain a given flexibility of the flexible, multilayer circuit substrate, for example in one or more preferred winding directions.

In the technical field of printed circuit board production, flexible substrates, in particular with copper conductor tracks, are frequently produced in a volume production. Such flexible substrates or substrate films, which are also referred to as flex films, have, for example, a substrate thickness of 25 μm, 50 μm or 125 μm. If two or more such flex films are laminated together or glued together, a flex film stack (film stack) results, which has a significantly lower flexibility than a single flex film. Such flex film stacks are exposed to high, site-specific bending stress or shear stress loads, in particular in the case of a bending load, which can lead to mechanical damage of the flex film stack even after a few bending operations or bending cycles.

10 now shows a known circuit substrate 100 according to the prior art with a substrate film 101 , Tracks 102 and a protective layer 103 , On a first main surface 101 the substrate film 101 are tracks 102 , which consist for example of a copper material applied. As in 10 is shown, are the tracks 102 on their exposed surfaces of the protective layer 103 surrounded or embedded therein, wherein, as in 10 is shown, usually the topography of the tracks 102 through the protective layer 103 is not completely leveled. This film substrate referred to as a flexible insert substrate 100 now has, for example, a flexibility or flexibility X ₀ , which depends on the material properties of the substrate film 101 , the conductor tracks 102 and the protective layer 103 and the thickness d _{0 of} the film substrate 100 depends.

For describing the flexibility of a substrate assembly, the number of bending cycles, i. E. H. bending operations by a certain bending angle, until, for example, a failure of the electrical function or mechanical damage occurs. Such defects can be manifested, for example, in the breakage of a conductor track, a detachment of a contact or a delamination of the layer structure.

The number of bending cycles up to an electrical or mechanical defect depends strongly on the respective bending radius of the film substrate. Small bending radii, which result in a strong deformation of the respectively affected material areas, may even after a relatively small number of bending operations lead to an electrical or mechanical defect. For large bending radii with a relatively small mechanical deformation of the respective substrate areas, a very high number of bending cycles, for. B. several million bending cycles can be achieved without a defect occurs on the layer substrate.

Regarding the in 10 illustrated film substrate 100 it is also noted that the tracks 102 (as in 10 shown) directly on the main surface 101 the substrate film 101 are arranged, equally between the interconnect layers 102 and the surface 101 the substrate film 101 still an adhesive layer (not shown in FIG 10 ) may be present. Both described alternatives according to the 10 ie with or without adhesive layer between the tracks 102 and the substrate surface 101 , are thus to be regarded as a single-layer film substrate or insert flex substrate.

Based on 11 now becomes a multilayer film substrate 120 represented according to the prior art. As in 11 are two (or more) substrate planes, ie, insert flex substrates, as exemplified by 10 were described, glued together or laminated. Thus, the first substrate level 100 again the substrate film 101 , the tracks 102 and the protective layer 103 on. Accordingly, the second substrate level 110 a substrate film 111 , Tracks 112 and a protective cover 113 on.

To the mutual connection of the first single-layer film substrate 100 with the second single layer film substrate 110 is between the two film substrates 100 . 110 an adhesive layer 104 for the entire surface connection of the first and second single-layer film substrate 100 . 110 arranged. This results in a total thickness d ₁ of in 11 shown overall arrangement 120 , ie the multilayer film substrate shown there 120 , Due to the adhesive material 104 full-surface connected single-layer film substrates 100 . 110 arises each according to the nature of the adhesive material 104 and the material for the protective layers 103 . 113 for the overall arrangement, ie for the multilayer film substrate 120 , opposite to in 10 shown single-layer film substrate 100 a significantly reduced flexibility or flexibility X ₁ . Thus, for example, with the same force in the multilayer film substrate 120 from 11 a significantly lower bend compared to the 10 shown single-layer film substrate 100 be achieved.

12 shows now possible stress gradients at a bending stress of in 11 shown multilayer film substrate 120 about the thickness d ₁ . For example, in the multilayer film substrate 120 exerted a bending stress, z. B. by the force F (in 12 vertically downwards in the drawing plane), the results in 12 in principle illustrated mechanical layer stress distribution over the total layer thickness d ₁ due to micromechanical forces that oppose the bending force F. As in 12 shown, arise along the thickness d _{1 of} the multilayer film substrate 120 in the direction of the upper main surface 120a of the multilayer film substrate 120 increasing tensile forces while moving towards the lower major surface 120b of the multilayer film substrate 120 increasing pressure forces due to the bending force or bending stress F result. At a bending stress of the multilayer film substrate 120 from 11 for example, the tensile forces lead to a material expansion and the compressive forces lead to a material compression of the corresponding regions of the multilayer film substrate 120 , As long as an elastic limit of the multilayer film substrate of 11 is not excessive thickness stress, is the deformation of the multilayer film substrate 120 reversible.

Regarding the in 10 and 11 shown single or multilayer film substrates 100 respectively. 120 It should be noted that the respective tracks are not only on one of the major surfaces of the substrate films or flex substrates 101 . 111 , but also on opposite main surfaces can be arranged. In addition, electrical contacting compounds, such as. B. Durchführungsungskontaktierungen (vias), between interconnects of opposing main surfaces (ie back and front) or be present to metallization. Thus, in particular in the case of electrical connections in the form of plated-through holes through the respective foil substrates, at least local stiffening of the resulting foil substrate and thus a reduction in the flexibility or flexibility of the overall arrangement, since the plated-through holes in the form of metal sleeves, for example, have a high local rigidity. Applied bending forces or bending stresses can thus cause so-called sleeve breaks of the plated-through holes or a delamination of the individual layers.

Furthermore, with the in 10 and 11 illustrated single or multilayer film substrates 100 respectively. 120 on one of the major surfaces in the film substrates used 100 respectively. 110 be arranged and integrated electrical or electronic components. As electrical components components with passive electrical properties are summarized, for. As resistors, capacitors and inductors, while as electronic components further components with active electrical properties, eg. B. semiconductor chips are called. The electrical contacting of these electrical or electronic components can be realized for example by means of electrically conductive adhesives or by a solder material, unless they are contacted directly by screen printing with the conductor tracks, for example. At a bending stress of the overall arrangement, ie the multilayer film substrate 120 Now, the joints between traces and electrical or electronic components can be mechanically damaged or break. The risk of breakage is directly related to the strength of the applied bending stress.

Based on this prior art, the object of the present invention is therefore to provide a flexible, multilayer circuit substrate and a method for producing the same, in which the resulting multilayer film substrate is on the one hand very resistant to possible bending stresses and on the other hand specifically adaptable to predetermined bending stresses.

This object is achieved by a flexible, multilayer circuit substrate according to claim 1 or 16 and by a method for manufacturing a flexible, multilayer circuit substrate according to claim 19 or 32.

The core idea of the present invention is to enable an improved arrangement and topology for the assembly of film substrates with electrical and / or electronic functions to flexible, multilayer circuit substrates by having the two individual film substrates only at geometrically predetermined, spatially separated connection positions with an example two-layer film substrate a connecting material, such. As adhesive or solder material, are connected. Here, the arrangement of the mechanical connection points as well as their geometric extent and Distribution selected so that a desired bending radius, for example along a preferential bending line results in at least a portion of the resulting flexible multilayer circuit substrate. Thus, according to the invention geometric areas and their orientation or arrangement are defined to each other, in which a mechanical connection, for. B. adhesive connection or solder joint, and possibly also electrical connections are arranged. These connection areas are spatially separated from each other and arranged with a predetermined minimum distance from each other. Thus, contiguous geometric regions between opposed major surfaces of the first and second flexible film substrates to be bonded have bonding material for mechanical fixation only at predetermined discrete bonding regions. The mechanical connection areas between the opposing major surfaces of the first and second flexible film substrates to be joined are now in accordance with a given geometrical relationship between the extent of the separated connection areas and the distance between adjacent connection areas, ie the extension of connectionless areas, such as geometric dimensions For example, the film thickness and the thickness of the bonding material derived at the connection areas, so that in the connection of two flexible film substrates to a resulting flexible, multilayer circuit substrate is achieved over the present prior art, on the one hand improved flexibility and selectively adjustable flexibility. In particular, subsections of the resulting flexible, multilayer circuit substrate can thus be designed so that they can be subjected to a predetermined bending stress. For this purpose, a predetermined bending radius (target bending radius), for example, has a predetermined preferred bending direction, based on the dimensions and material properties of the flexible film substrates used or on the flexible, multi-layer circuit substrate or at least in parts thereof by the targeted arrangement and design of the connection areas. of the connecting material and its base, thickness and spacing.

If, for example, in a flexible, multilayer circuit substrate in the form of a film stack or film substrate stack, certain subregions or regions are (presumably) exposed to different bending requirements, then different geometric configurations of the mechanical connection regions and their arrangement may depend, for example, on a thickness (minimum thickness) of the connecting material on the Connection areas and an achievable target bending radius, the distances of adjacent or opposite mechanical connection areas are selected to set the desired bending radius (at least partially) or change. For example, assuming a linear orientation of the connection regions, the distance (minimum distance) of opposing mechanical connection regions is selected according to the desired bending radius to be set. According to the invention, in particular the distance z. B. opposite connection areas, which are arranged along adjacent connecting lines, larger than a dimension such. As the diameter, the side length or the width of the connection areas to choose. According to the invention, the mechanical connection areas are to be understood as self-contained "point-like" or strip-shaped structures which are arranged separately from one another. The effective or effective dimension of the connection regions results, for example, from the extent of the respective connection region in the direction of an opposite connection region, which is located in an adjacent connection region, and z. B. through the geometric center or center of this connection area.

Flexible, multilayer circuit substrates can now be designed in particular such that they are designed at least in regions for a given bending requirement, by virtue of these regions having a desired bending radius, ie. H. an adjustable or achievable bending radius.

Based on the concept according to the invention, a topology can now be found for a flexible, multilayer circuit substrate in order to achieve a flexibility or flexibility in the case of an assembly of at least two flexible film substrates (flex films or insert flex films) with electrical and / or electronic functions resulting film stack, d. H. of the resulting flexible, multilayer circuit substrate, which on the one hand is not significantly reduced compared to individual film substrate arrangements and on the other hand can be adjusted in a targeted manner according to predetermined bending stresses. In addition, the procedure of the present invention for designing the topology of a flexible, multilayer circuit substrate achieves that the overall location of the film stack significantly reduces the site-specific bending stress or shear stress load that is possible with conventional multilayer circuit substrates.

Preferred embodiments of the present invention will be explained below with reference to the accompanying drawings. Show it:

1a FIG. 3 shows schematic diagrams of a flexible, multilayer circuit substrate having respective connection regions according to an embodiment of the present invention; FIG.

2a -D is a schematic diagram of the geometric arrangement of connection regions of the flexible multilayer circuit substrate according to another embodiment of the present invention;

3a -D schematic diagram of the geometric arrangement of the connection areas in a flexible, multilayer circuit substrate according to a further exemplary embodiment of the present invention;

4 a schematic plan view of a flexible multilayer circuit substrate according to another embodiment of the present invention;

5 a schematic cross-sectional view of a flexible multilayer circuit substrate according to another embodiment of the present invention;

6 a schematic cross-sectional view of a flexible multilayer circuit substrate according to another embodiment of the present invention;

7 a schematic cross-sectional view of a flexible multilayer circuit substrate according to another embodiment of the present invention;

8th a schematic cross-sectional view of a flexible multilayer circuit substrate according to another embodiment of the present invention;

9a FIG. 5 shows flowcharts of a manufacturing method for a flexible multilayer circuit substrate according to another embodiment of the present invention; FIG.

10 a schematic cross-sectional view of a single-layer film substrate according to the prior art;

11 a schematic cross-sectional view of a multilayer film substrate according to the prior art; and

12 a schematic representation of the bending stress across the thickness of the multilayer film substrate according to the prior art.

Before the present invention is explained in more detail in detail with reference to the drawings, it is pointed out that identical, functionally identical or equivalent elements are provided in the figures with the same reference numerals, so that the description of these elements shown in different embodiments is interchangeable or can be applied to each other.

The following will now be based on 1a Figure 1 shows a first embodiment of a flexible multilayer circuit substrate according to the present invention.

1a shows in a schematic plan view of at least a partial area 12 a flexible, multilayer circuit substrate 10 with the rectangular connecting areas 32 , For ease of illustration and description, only 16 connection areas 32 illustrated by way of example, wherein the following explanations to an i. W. any number of connection areas 32 is applicable.

Like now in 1b in the form of a cross-sectional view of the flexible, multilayer circuit substrate 10 are shown are the connection areas 32 provided to a first single-layer film substrate 20 and a second single layer film substrate 40 to connect with each other. As in 1b is shown, has the single-layer film substrate 20 an insert flex film or substrate film 22 on. The second substrate level 40 of the flexible, multilayer circuit substrate according to the invention 10 now has, for example, a further substrate film or an insert Flex substrate 42 on. At the in 1b shown flexible, multilayer circuit substrate 10 are the connection areas 32 z. B. directly on the single-layer film substrates 22 and 42 arranged and connected to the same. In the following exemplary embodiments, optional protective layers for the film substrates are still being used 22 respectively. 42 described, which then also with the connection areas 32 can be connected.

Like now in 1c in the form of a cross-sectional view of an optional embodiment of the flexible, multilayer circuit substrate 10 is shown, has the single-layer film substrate 20 for example, an electrical or electronic functional element 24 , z. B. a conductor track, on. Electrical or electronic functional elements are referred to below simply as functional elements.

The functional element 24 is for example with a protective layer 26 covered, with the protective layer 26 for example, not completely the Topography of the functional element 24 (eg a trace). With respect to the example designed as a conductor electrical or electronic elements 20 It should be noted that these z. B. still by means of an adhesive or an adhesive layer (not shown in FIG 1c ) on the main surfaces 22a or on the opposite main surface 22b the substrate film 22 can be arranged.

The second substrate level 40 of the flexible, multilayer circuit substrate according to the invention 10 now has, for example, a further substrate film or an insert Flex substrate 42 , electrical or electronic functional elements 44 . 46 and optionally a protective layer 48 on. On the upper main surface 42a the substrate film 42 are now optional the circuit elements 44 respectively. 46 arranged, in turn, by a protective layer 48 are surrounded. Also at the second substrate level 40 of the multilayer circuit substrate according to the invention 10 are the circuit elements 44 . 46 for example, not completely through the protective layer 48 embedded, leaving the topography of the circuit elements 44 . 46 for example, in the second substrate level 40 is not completely leveled. Of course, single or both protective layers 26 . 48 be formed to the surfaces of the substrate planes 20 . 40 completely level, for example, to obtain flat surfaces.

As in 1c is shown, is the electrical or electronic functional element 24 the first substrate level 20 offset to the connection areas 32 arranged while the electrical or electronic functional elements 44 . 46 the second substrate plane with the connection areas 32 are arranged aligned. The following explanations will show that the functional elements 24 . 44 . 46 depending on their flexibility, for example, preferably at certain areas of the first or second substrate level 20 . 40 of the multilayer circuit substrate 10 are arranged. If, for example, the flexibility of a functional element is sufficiently high, then this functional element can be connected to substantially any desired position on the associated substrate plane 20 . 40 be arranged. If, for example, the flexibility of one or more of the functional elements is significantly lower than that of the associated substrate planes 20 . 40 , these functional elements are, for example, in the region of the connection regions at the associated substrate level 20 . 40 arranged. The exact relationships will be explained more clearly below.

In the following, the geometric arrangement according to the invention for connecting the two substrate planes will now be described 20 . 40 used connection areas 32 received, as in the 1a C is shown by way of example. In the context of the present invention, it should be noted that optionally also other substrate planes (not shown in FIG 1b and 1c ) can be added. The inventive topology of the flexible, multilayer circuit substrate 10 In particular, mm deals with the mechanical and subordinate with the electrical connection of at least two sub-levels 20 . 40 , respectively, for example, an insert flex film substrate 22 respectively. 42 exhibit. According to the present invention, mm is represented as the connection areas 32 (with the connection material) z. B. in terms of footprint and thickness are formed, and in which geometric arrangement, the plurality of connection areas are to be arranged to each other to the inventive flexible, multilayer circuit substrate 10 to obtain. The targeted design of the flexibility of the multilayer circuit substrate according to the invention 10 takes place, for example, taking into account an achievable or adjustable bending radius R ₀ (nominal bending radius) of the flexible, multilayer circuit substrate 10 ,

The inventive topology of the flexible, multilayer circuit substrate 10 is characterized by the fact that geometric areas are defined as connecting areas 32 in which by means of the connecting material arranged there, a mechanical adhesive bond and possibly also an electrical connection between the two substrate planes 20 . 40 is formed, while other, coherent geometric areas have no mechanical connection. According to the invention, the specifications regarding the geometric relationship of the areas without mechanical connection (in the form of the effective distances B _{0 of} opposing connection areas 32 ) of the geometric dimensions of the respective thicknesses D ₂₀ , D _{40 of} the substrate planes 20 . 40 and the thickness D _{0 of} the bonding material 33 in the connecting areas 33 derived, so that overall an adjustable flexibility with increased bending load in appropriately trained sections 12 . 14 or completely in the flexible multilayer circuit substrate 10 is obtained.

Like now in the 1b and 1c is shown, the first substrate level 20 a thickness D ₂₀ , the second substrate plane 40 a thickness D ₄₀ and the connection areas 32 a thickness D ₀ . In addition, the connection areas indicate 32 (For example, starting from a rectangular or circular configuration), z. B. in a direction toward each other, a dimension A ₀ , while adjacent or opposite connecting regions 32 at least at a distance B ₀ are arranged away from each other. As in 1a are shown are the connection areas 32 rectangular and arranged in an orthogonal grid. As the following explanations will show, this arrangement and design of the connecting elements is to be regarded as exemplary only, with other possible configurations or geometrical arrangements of the connecting regions also being mentioned below 32 according to embodiments of the present invention will be explained.

1d now shows by way of example a bending deflection of the flexible, multilayer circuit substrate 10 due to the bending stress F. Due to the arrangement and alignment of the connection areas according to the invention 32 or connection areas 34 For example, a preferential bending direction BR, which results in 1d is given as an example perpendicular to a bending area along a preferred bending line BL. Perpendicular to the surface of the flexible, multilayer circuit substrate 10 and thus to the preferred bending line BL results in the resulting bending radius R ₀ due to the applied force F. According to the invention, the achievable bending radius R _{0 of} the flexible, multilayer circuit substrate 10 be adjusted and adjusted to the bending stress F (in the form of bending deformation of the flexible, multilayer circuit substrate 10 ) without being able to absorb mechanical damage.

Like now in 1a -D are the first substrate plane 20 and the second substrate plane 40 by means of in the connection areas 32 arranged connecting material, for. As an adhesive material, solder material, etc., mechanically interconnected. The connection areas are now at least in the subregions of the film stack 10 ie, the flexible, multilayer circuit substrate 10 For example, which are subjected to a predetermined bending stress, arranged so that a preferential bending direction of the flexible multilayer circuit substrate 10 (at least in the subarea). The connection areas 32 , which now have at most one dimension A ₀ and at least with a distance B ₀ from an adjacent connection area 32 are arranged separately, are now designed so that the distance B _{0 is} greater than the dimension A _{0 is} selected. Mm are the connection areas 32 symmetrical to each other, z. B. in a linear, parallel or in an orthogonal grid for connecting the first and second substrate plane 20 . 40 arranged, results in the resulting multilayer circuit substrate 10 a preferred bending direction of the flexible multilayer circuit substrate 10 (at least) in the correspondingly formed subarea. Are now the connection areas 32 For example, arranged in a linear parallel and / or an orthogonal grid to each other, so adjacent connection areas 32 for example, as in 1a 2, extend along a (eg, linear) connection line, respectively, to mating connection areas 34 be summarized. At the in 1a illustrated exemplary arrangement of the connection areas 32 now arise a plurality of mutually parallel connection areas 34 based on the respectively selected symmetry of the geometric arrangement of the connection areas 32 ,

Due to the example in 1a illustrated orthogonal rasters of the connection areas 32 arise, for example, according to a marked xy coordinate system parallel connection areas 34 in the x-direction, in the y-direction and in both diagonal directions. To simplify the view of 1a the connection areas are indicated only in a diagonal direction.

As now in particular from 1a should be apparent, alternatively, for example, preferential breeder judgments targeted, can be set or selectively prevented by, for example, in lines I, II, III and IV, the respective connection areas 32 each remain linearly arranged, but their distances within the associated connection area 34 be provided variable or non-constant or non-periodic to each other, so that forms a preferred bending line only along the x-direction and thus results in a preferred bending radius only substantially perpendicular to the x-direction. This specification of the geometric arrangement of the connection areas 32 is essentially for each of the in 1a illustrated connection areas 34 selectable. As an alternative to the in 1a Thus, for example, the connection areas shown 32 the connection areas arranged in the x-direction 34 arranged at a random, non-constant distance or at a very small distance (eg, smaller A ₀ ) to each other, so that only the aligned parallel to the x-direction connecting areas 34 result. Due to the lack of symmetry, no connection areas are formed in the y-direction or in the diagonal direction 34 ,

From the above it should be clear that to define the connection areas 34 , the connection areas arranged symmetrically to each other 32 have the dimension A ₀ as the diameter of the connecting portions 34 and the distance B ₀ as the distance of the connection areas 34 can be accepted.

The effective or effective dimension of the connection regions results, for example, from the extent of the respective connection region in the direction of an opposite connection region, which is located in an adjacent connection region, and z. B. through the geometric center or center of this connection area.

According to further embodiments of the present invention, the connection areas 32 at least in the subarea 12 flexible, multi-layered circuit substrate 10 be arranged with respect to diameter, thickness and distance from each other to obtain an achievable or adjustable bending radius (target bending radius) R ₀ , which is the associated portion 12 flexible, multi-layered circuit substrate 10 should at least follow at a bending stress.

Now, for example, a target bending radius R ₀ at a spacing B _{0 of} the connection areas 32 with respect to adjacent connection areas 34 and at a predetermined minimum thickness D ₀ in the subregion 12 flexible, multi-layered circuit substrate 10 provided, this can be achieved by the following mathematical description or condition is met:

In this context, the factor α _{0 is} referred to as tolerance factor, in the example, boundary conditions with respect to the properties of the substrate level used 20 . 40 , Track arrangements, arrangements of the functional elements, etc., enter. For example, depending on the design of the boundary conditions, the tolerance factor should be selected with α ₀ = 0.4 to 1 or α ₀ = 0.7 to 1 (and, for example, α ₀ = 0.8 or α ₀ = 1).

gewählt werden. Ferner wird darauf hingewiesen, dass als eine obere Begrenzung B_0-max für den zu wählenden Abstand B₀ beispielsweise folgender Wert vorgesehen sein kann:

For example, in a realization of a flexible, multi-layered circuit substrate, the distance

to get voted. It should also be noted that, for example, the following value can be provided as an upper limit B _0-max for the distance B _{0 to} be selected:

For the distance B _{0 to be selected} for a given desired bending radius R ₀ , the following secondary conditions are also used: B ₀ <R _0/4 and B ₀ > A ₀ .

Regarding the above conditions for the distance B _{0 to be selected} between adjacent connection areas 32 or adjacent connection areas 34 It is further noted that the thickness D ₂₀ , D _{40 of} the substrate plane 20 . 40 much lower (eg, less than 5%) than the desired bend radius R _{0 of} the resulting substrate stack, ie, the flexible multilayer circuit substrate 10 to be chosen as another constraint: D ₂₀ << R ₀ ; D ₀ << R ₀ ; D ₄₀ << R ₀ .

Regarding the above main condition, it should be noted that these are substantially the order of magnitude of the geometrical relationships of the dimensions and the arrangement of the connection areas 32 with respect to the dimensions of the substrate planes 20 . 40 where the tolerance factor α _{0 is to} take into account further possible boundary conditions for the above main condition.

Thus, according to an embodiment of the present invention, at least a portion 12 or the entire circuit substrate formed as a flexible layer stack 10 that the connection areas arranged according to the invention 32 have to be formed with the desired target bending radius R ₀ , to be adapted for example for a predetermined bending stress.

According to further embodiments of the present invention, for example, further subregions of the layer stack may be used 10 be provided with different desired target bending radii R ₀ , R ₁ , so that different areas of the film stack can be exposed to different bending requirements. Thus, according to the above relationships, the distance of the mechanical connection areas 32 taking into account the further geometric dimensions of the first and second substrate planes 20 . 40 and the minimum thickness D _{0 of} the bonding material in the bonding areas 32 in the subset to be set 12 of the film stack 10 be set. The distance of the mechanical connection areas 32 or the adjacent connection areas 34 can therefore be changed with the variation of the intended bending radius R _{0 to} be provided. In this context, it is pointed out that the geometric dimensions which are measured as dimension A _{0 of} the connection regions or distance B _{0 of} the connection regions in 1a Are not shown to scale to each other. Only the distance B of the connection areas 32 is (to scale) larger than the width A _{0 of} the connection areas 32 or the connection areas 34 specified. In this context will again noted that the connection areas 32 or the connection areas 34 are to be understood as self-contained punctiform or strip-like structures, and thus differ significantly from contiguous adhesive layers.

According to a further embodiment of the present invention can now in a further sub-area 14 flexible, multi-layered circuit substrate 10 a plurality of further connection areas 32 be provided, which in turn are arranged separately from each other. According to the preceding embodiments, again a plurality of associated connection areas 32 an associated connection area 38 form. In particular, the connection areas 32 along linearly extending, adjacent connection areas 34 be arranged, wherein each of the further connection areas 34 each an elongated, further connection area 32 or a plurality of separate, further connection regions 32 having. The other, adjacent connection areas 34 then have, for example, the further dimension A ₁ and are arranged at least in the further distance B ₁ . In this case, in turn, the further distance B ₁ (the adjacent, further connection areas 34 in the further subarea 14 ) considering another target bending radius R1 of the flexible multilayer circuit substrate 10 fulfill the following condition:

As a further constraint with respect to the further distance B ₁ with respect to the further desired bending radius R ₁ and the further dimension A ₁ , the following condition results, for example: B ₁ <R _1/4 and B _{1> A1.}

In this context, the factor α _{1 is} again referred to as a tolerance factor, in the example, boundary conditions with respect to the properties of the substrate level used 20 . 40 , the conductor track arrangements, the arrangements of the functional elements, etc., enter. For example, depending on the knowledge of the boundary conditions, the tolerance factor should be selected as α ₁ = 0.4 to 1 or α ₁ = 0.7 to 1 (and, for example, α ₁ = 0.8 or α ₁ = 1).

gewählt werden. Ferner wird darauf hingewiesen, dass als eine obere Begrenzung B_1-max für den zu wählenden Abstand B₁ beispielsweise folgender Wert vorgesehen sein kann:

For example, in a realization of a flexible, multi-layered circuit substrate, the distance

to get voted. It should also be noted that, for example, the following value can be provided as an upper limit B _1-max for the distance B _{1 to} be selected:

Regarding the above main condition, it should be noted that these are substantially the order of magnitude of the geometrical relationships of the dimensions and the arrangement of the connection areas 32 with respect to the dimensions of the substrate planes 20 . 40 where the tolerance factor α _{1 is to} take into account further possible boundary conditions for the above main condition.

Flexible substrates or substrate films, which are also referred to as flex films, for example, have a substrate thickness D ₀ in a range of 1 .mu.m to 200 .mu.m and for example values of 25 .mu.m, 50 .mu.m or 125 .mu.m or intermediate values thereof. With sufficient flexibility of the flex films, layer thicknesses of up to about 500 μm are also conceivable. Similarly, with a sufficient strength of the flex films, layer thicknesses of less than 1 μm are conceivable.

The following are now based on the 2a -D possible alternative implementations for the geometric arrangement of the connection areas 32 or connection areas 34 explained in more detail.

2a For example, now set two parallel connection areas 34 with the connection areas arranged therein 32 In a parallel and linear alignment of the connection areas 32 and thus the connection areas 34 the distance B ₀ results between the distance between two opposite connection areas 32 of two adjacent, parallel connection areas 34 , Thus, the distance B ₀ is a "minimum distance" between the two connection areas 34 to watch. 2a now also shows the connection areas 32 in the form of circular areas. However, in accordance with the invention, rectangular, square, oval, or any desired basic shapes for the connection regions can equally well be used 32 can be selected, as long as they are technically useful and suitable to produce, where as the distance B ₀ then the smallest distance between the dimensions of the connection areas 32 in adjacent connection areas 34 represents. For example, the dimension of the connection areas 32 within a tolerance range of, for example, <± 10%, as long as this tolerance range for the dimension is small (eg <10%) compared to the distance B ₀ between the adjacent connection regions 34 is.

2 B now shows a representation of the connection areas 32 adjacent connection areas 34 , where the connection areas 32 a connection area 34 are each arranged linearly, the connection areas 32 a connection area 34 to the connection areas 32 of the adjacent connection area are offset by a variable or constant offset Δx. At the in 2 B shown partial view of separately arranged connection areas 32 in two adjacent connection areas 34 can the distance B ₀ as a minimum distance of the two adjacent connection areas 34 be considered. With a relatively small offset Δx (with Δx ≤ 0.1 B ₀ ), the in 2 B drawn distance B _0x to determine the desired topology of the connection areas 32 be used, ie the distance of a connection area 32 in a connection area 34 to the next adjacent connection area 32 in the adjacent connection area 34 ,

2c now shows a schematic representation of connection areas 32 in adjacent connection areas 34 , As in 2c is shown, the connection areas in the adjacent connection areas 34 also have a different base area, again as a distance B ₀ (minimum distance), the distance of the adjacent connection areas 34 is to be considered. Likewise, according to the invention, individual connection regions can likewise be used 32 a connection area 34 have a different size, but for determining the minimum distance B ₀ each (in terms of their extent) the largest connection areas 32 or the closest approximate connection areas 32 between two adjacent connection areas 34 the outline of the respective connection area 34 and thus define the minimum distance B ₀ . It should also be noted that according to the present invention and that in 2c illustrated arrangement, the effective dimension A _0, for example, based on the connection areas with the largest extent.

2d now shows a geometric arrangement of the connection areas 32 of two adjacent connection areas 34 in which the connection areas of at least one connection area are not aligned on a straight line, but z. B. on a portion of a circular arc or other curve. As with the in 2 shown arrangement, the minimum distance B ₀ results as the smallest distance between the two adjacent connection areas 34 ,

The bending line results in embodiments with parallel and in a straight line to each other arranged connection areas preferably along the center lines to the. Connecting areas. Now, if the orthogonal arrangement of the connection areas is abandoned and a "bent" arrangement is present, there is a variation of the axis of the bending line and thus a variation of the preferential bending direction. This could be useful in (rare) applications where the alignment of the bendline should have a tolerance due to parallelism errors. However, curved arrays of interconnect areas result in a reduction in bendlines per unit area on the film since the bendline is a straight line and the spacing of two bendlines in the curved array case is determined by the vertices of the bend.

Essentially, it can be assumed that many small bends along many parallel bending lines lead to an overall bending radius of the film stack, cf. Approximation of a circle by tangent segments.

The in the 2a -D shown further embodiments, such as the maximum of the connection areas 32 or connection areas 34 assumed dimension A ₀ and the associated minimum distance B ₀ between adjacent connection areas 32 or connection areas 34 is applicable. Furthermore, in the 2a -D shown arrangements of the connection areas 32 or the connection areas 34 be combined, ie one of the upper connection areas 34 in the 2a Each with one of the lower connection areas in 2a d.

A film is, if only minor internal mechanical stress is to be present, only one-dimensional and therefore perpendicular to parallel bending lines possible, such. B. a foil which is bent into a cylinder jacket. In 2a result for the bending lines a main preferred direction in the x-direction (in west-east direction) and a minor preferred direction in the y-direction (in north-south direction). In 2 B For the bending lines, a principal preferred direction in the x direction (in the west-east direction) and a minor preferred direction in a diagonal xy direction (in the NNW-SSO direction) are obtained. In 2d results in a main bending line with tolerance range x-direction (in west-east direction).

A combination is z. B. permissible to the extent that at least one main preferential direction for a bend remains, according to which a shaping of a cylinder jacket or a cone sheath is possible. The bending radius (see snail shell) and the curvature orientation (see corrugated sheet metal) may vary. If a cone sheath was desired as the bending shape, the connecting regions can be arranged along conical sheath lines through the cone tip, so that no orthogonal checkerboard pattern of connection areas would result.

The following are now based on the 3a -D possible embodiments of the connection areas described above 32 or the associated connection areas 34 described. As already stated above, a connection region has an elongate, contiguous connection region or a plurality of separate, mutually aligned connection regions, ie a connection region 34 is a contiguous area or is in sections into individual connection areas 32 divided, for example, are aligned linearly with each other, that are arranged along a connecting line. Are now the connection areas or the associated connection areas z. B. aligned linearly or along a connecting line to each other, a bending region or preferential bending region with a preferred bending direction can be formed between these connection areas. Are still the basis of the 1a -Federation 2a -D shown conditions with respect to the geometric configurations and dimensions of the substrate planes 20 . 40 and the connection areas 32 and the connecting material arranged therein, so by setting the distance (minimum distance) B _0, a target bending radius R _0, for example, in a preferred direction with respect to the surface of the flexible multilayer circuit substrate 10 be achieved.

3a shows mm schematically the geometric arrangement of the connection areas 32 between the two substrate planes 20 . 30 (not shown in 3a ) of the flexible multilayer circuit substrate of the present invention 10 , As in 3a is exemplified, all have connection areas 32 a rectangular shape with a side length A ₀ . Since the arranged in an orthogonal grid connection areas 32 each further to the orthogonally adjacent connection areas 32 have a distance B ₀ , resulting in terms of in shape 3a shown preferred geometric reference lines each, which are aligned according to the drawn orthogonal x- / y-coordinates. The corresponding desired bending radii R ₀ arise perpendicular to these preferred bending lines. At the in 3a illustrated embodiment form mutually orthogonal connection areas 32 and optionally also diagonally aligned connection areas 32 each one connection area 34 ,

3b now shows an arrangement of connection areas 32 in which the distance B ₀ in a partial area 14 opposite a subarea 12 has doubled, so that in the subarea 14 yield preferential bending or preferential bending lines both along the orthogonal axes of the x / y coordinate system and in both diagonal directions. The in 3b shown subareas 12 . 14 For example, those already in 3a illustrated basic properties, wherein in the sub-area 14 one opposite the subarea 12 due to the different spacing of the connecting portions, a different desired bending radius R ₀ can be realized. In 3b each form orthogonally aligned connection areas 32 and optionally also diagonally aligned connection areas 32 each one connection area 34 ,

The drawn (dashed lines) bending lines are synonymous conceivable with generatrices on a cylindrical surface. A simple idea guide might be the process that occurs when wrapping a bottle. Bottle body and bottleneck have a different bending radius. If a film (eg paper) is wrapped around the bottle, this can not be accomplished without wrinkles at the transition from bottle body to bottle neck, because there the one-dimensional bend merges into a two-dimensional bend. Stress-free ie wrinkle-free is not possible. As shown by 3b are different bending radii but "wrinkle-free" possible.

Like now in 3c are shown are the connection areas 32 provided with an elongated base, so that parallel connection areas only along the alignment of the connection areas 32 , that is to say in the y-direction, which satisfy the relationship B ₀ > A ₀ . This results in preferred bending ranges only parallel to the orientation of the connection areas 32 or the connection areas 34 ie in the x-direction. At the in 3c illustrated embodiment form, for example, six, linearly aligned in the x-direction connection areas 32 a connection area 34 , The preferred direction for a dimensioning according to the invention to a bend would be seen here by the following train of thought. The distance between the connection areas 32 in the x-direction, the constraint B ₀ > A ₀ does not satisfy. In the y-direction, this constraint is fulfilled. Furthermore, the connection regions are arranged in parallel and thus results in a bend corresponding to a cylinder jacket and, in turn, therefore, the preferred direction of the generatrices in the x-direction. Since the connection regions are regularly spaced in the y-direction, this embodiment is preferably suitable for a constant bending radius (cf bend around a cylinder jacket surface).

As a continuation of the in 3c illustrated embodiment is now in 3d a Arrangement of the connection areas 32 shown in which they are shown as elongated, contiguous geometric shapes, so that a connection area 32 equally a connection area 34 represents.

Regarding in the 3a -D illustrated arrangements should be noted that the distances of adjacent connection areas 34 may also be formed variable, based on the smallest distance B ₀ between two adjacent connection areas 34 the expected target radius R _{0 is} adjustable.

Regarding the in 3a -D illustrated implementations for the arrangement of the connection areas 32 or the associated connection areas 34 It should be noted that these are uniform over the entire film stack, ie the flexible, multilayer circuit substrate 10 , can be distributed or on at least a subarea 12 . 14 flexible, multi-layered circuit substrate 10 are limited. Furthermore, the geometric arrangement of the connection areas 32 or the connection areas 34 in the layer stack to vary for different portions of the layer stack 10 specify different desired bending radii R ₀ , R ₁ , etc.

In this context, however, it is pointed out that for layer stacks with more than two substrate planes, the connection regions assigned to the respective substrate planes 32 with respect to projection through the substrate planes within a projected footprint of the desired bond areas 34 to the desired preferred and preferred bending ranges of the resulting layer stack 10 to ensure even in the presence of a larger number of substrate levels.

In 4 FIG. 12 is a schematic plan view (in a see-through view) of the flexible multilayer circuit substrate. FIG 10 according to another embodiment of the present invention. In particular, for example, the section line SS of in 1c Corresponding sectional view correspond.

As in 4 are shown are the connection areas 32 For example, formed as elongated rectangular areas (see, for example, the 3c and d), where further the in 1b illustrated functional elements 24 . 44 and 46 are shown in the form of electrical conductors. As 4 in particular, it can be seen, the courses of the conductor tracks 24 . 44 . 46 not on the areas of the mechanical connection areas or adhesive bonding areas 32 limited but can, if the interconnects 24 . 44 and 46 have sufficient flexibility, essentially arbitrary along the substrate planes 20 . 40 (not shown in 4 ).

As already mentioned above, the forms of training of the linked areas 32 for example, in the entire film stack 10 be the same or from a neighboring connection area 34 to another adjacent connection area 34 vary. Thus, in addition to oblong or rectangular formed connecting areas 32 also square or round, oval or circular connection areas 32 be provided, for example, a plurality of these connection areas 32 in a grid arrangement of connection areas 32 and intervening spaces are arranged and due to the grid arrangement or symmetrical alignment of the connection areas 32 or the resulting connection areas 34 Preferred directions for flexibility in a bending stress of the resulting film stack 10 result. In the case of strip-shaped mechanical connection regions (for example in the form of adhesive strips), the preferred direction results in bending perpendicular to the strip direction. That is, bending areas of the film stack 10 form, for example, parallel to the connection areas 34 out.

5 now shows another embodiment a flexible, multilayer circuit substrate 10 in which, for example, an electrical connection between the front and back of the film substrate 20 is provided, this electrical connection by means of a via (Via) 50 in areas outside the mechanical connection areas 32 between the major surfaces of a film substrate 22 are arranged. In 5 is such a via 50 shown schematically and without pretension to scale. In addition to the in 5 illustrated shaping of the via 50 are essentially any other possible embodiments for the realization of vias according to the invention applicable. So the actual training form of contacting 50 influenced by the specific manufacturing method for such vias. So how in 5 is shown, such a via is located between two main surfaces of the substrate plane 20 in areas without mechanical connection areas 32 ie in so-called B ₀ areas. The others in 5 shown elements already have the basis of 1b described functionalities. In addition, the in 5 arrangement shown yet another protective layer 28 at the lower major surface of the film substrate 22 on.

6 now shows in a schematic sectional view of another embodiment of a flexible, multilayer circuit substrate 10 in that an electrical connection between the front side (the first main surface) of the first substrate plane 20 to the front side (the first main surface) of the second substrate plane 40 by means of a via 52 is made. Such vias 52 from a major surface of a first substrate plane to a remote major surface of the second substrate plane 40 For example, in areas of mechanical connection areas 32 in which also the connecting material 33 is made. 6 shows an example of such a via 52 (Via) schematically and without pretension to scale. Again, it should be noted that the shape shown or the final configuration of the via 52 in the sectional view is not limited to this representation, but is essentially influenced by the particular manufacturing method used for such vias. The others in 6 shown elements already have the basis of 1b described functionalities.

From the perspective of the mechanical stress situation on electrical or electronic functions in the flexible, multilayer circuit substrate 10 (Film stack), it is advantageous if the integration of the functional elements takes place in layer areas with a low layer stress. Thus, for example, results accordingly 7 a possible realization of an electrical connection between two on opposite main surfaces of the first and second substrate plane 20 and 40 arranged conductor track 24 and 44 in that such contacting 54 (Via) from the track 24 the (upper) substrate level 20 to the track 44 the lower substrate level 40 ie in the inner layer area of the layer stack 10 is realized in the field of mechanical connection areas, for example by the mechanical connection material 33 at least partially by means of a z. As conductive adhesive or a solder material is formed to the electrical connection between the two on the different substrate levels 20 . 40 opposite tracks 24 . 44 manufacture. In addition, the in 7 arrangement shown yet another protective layer 28 at the lower major surface of the film substrate 22 on.

Regarding the basis of the 5 . 6 and 7 illustrated embodiments of the inventive flexible, multilayer circuit substrate 10 should be clear that the realizations of the vias 50 . 52 and 54 of course also in combination with each other at different positions of the flexible, multilayer circuit substrate 10 are feasible.

In 8th is now schematically in a side or sectional view one between two tracks 62 . 64 the first substrate level arranged electrical or electronic functional element 60 in a layer structure at the first substrate level 20 shown. For example, the functional element 60 as a resistive element in the film stack 10 be educated. So is between the tracks 62 and 64 of the first film substrate 20 a corresponding material layer for that resistive element 60 on the surface of the lower major surface of the first film substrate 20 arranged. The arrangement of the functional element 60 in the inner layer is advantageous in terms of mechanical stress situation. Instead of the functional element 60 The layer structure of a capacitor (eg plate capacitor) can likewise be integrated in the form of a resistive layer. Furthermore, it should be noted that essentially any functional elements, ie electrical or electronic components having sufficient flexibility on the inner layer of one of the substrate substrates of the substrate level 20 respectively. 40 can be arranged. Thus, for example, thinned semiconductor chips that have sufficient flexibility as a functional element at one of the substrate level 20 . 40 to be ordered. Thus, for example, semiconductor chips can be thinned down to several 10 μm (eg ≦ 50 μm) so that their permissible bending radius (before the occurrence of electrical or mechanical damage) is smaller than the desired bending radius R ₀ of the set or achievable target according to the invention, flexible, multilayer circuit substrate 10 , For example, Si chips begin to become flexible from a residual thickness of about 50 microns.

As electrical components are combined in the context of the present invention, components with passive electrical properties, for. B. resistors, capacitors and inductors while as electronic components, for example, devices with active electrical properties, eg. B. semiconductor chips are called. The electrical contacting of these electrical or electronic components can be realized for example by means of electrically conductive adhesives or by a solder material, unless they are contacted directly with the printed conductors, for example by screen printing or aerosol printing or inkjet printing.

It should be clear, however, that the in 8th illustrated embodiment of a layer-shaped functional element 60 on the inner layer of the upper film substrate 20 is not a final implementation specification, but arrangements of functional elements also on the inner layer of the lower film substrate 40 or on outer layers of the film substrates 20 . 40 are also feasible. In the 8th illustrated arrangement of the functional element 60 on the inner layer of one of the film substrates 20 . 40 but due to a relatively low stress layer stress at a bending stress of the layer stack 10 a possible realization. Thus, all possible combinations of the above-described embodiments and shown arrangements of conductor tracks, functional layers and functional elements on the respective front and back of one of the film substrates 20 . 40 the film stack, ie the flexible, multilayer circuit substrate 10 , can be achieved within the scope of the topology according to the invention.

9a Figs. 1 b show flowcharts of optional manufacturing methods for manufacturing a flexible, multilayer circuit substrate, and more particularly, a method of manufacturing a flexible, multilayer circuit substrate 10 with an achievable or adjustable nominal bending radius R ₀ at least for partial regions of the flexible, multilayer circuit substrate.

As in 9a is shown in both manufacturing processes 80 first at a step 82 a first and second flexible film substrate provided. It has at least one subarea 12 a major surface of the first and / or second flexible film substrate 20 . 40 a plurality of separately arranged connection areas 32 a connecting material. The connection areas 32 have a maximum dimension A ₀ and are spaced at least a distance B ₀ from an adjacent connection area, wherein the distance B _{0 is} greater than the dimension A ₀ . The bonding material at the connection regions has at least a thickness D ₀ for spacing the first and second flexible film substrates.

In another step 84 now becomes the first and the second flexible film substrate 20 . 40 at least in the partial area by means of the connecting material at the separate connection areas 32 interconnected to the flexible, multi-layered circuit substrate 10 manufacture.

In the process 80 For example, the bonding material will be at the bonding areas before or during the providing step 82 on the first and / or the second flexible film substrate 20 . 40 applied. The connection areas 32 For example, are symmetrical to each other, such. In a linear parallel or in an orthogonal grid, on the major surface of the first and / or the second flexible film substrate 20 . 40 arranged after connecting the first and second flexible film substrates 20 . 40 a preferred bending direction of the flexible multilayer circuit substrate 10 at least in the subarea 12 to obtain. The connection areas 32 For example, they may have a round (eg circular), an oval, a rectangular or a polygonal basic shape.

In the applying step, for example, adhesive material may be used as portions of a double-sided adhesive film, or by stencil printing or screen printing, or a solder material as the bonding material at the bonding areas 32 on the main surface of the first and / or the second film substrate 20 . 40 be applied. In addition, layer-shaped, electrical or electronic functional elements on the first and / or second film substrate 20 . 40 be arranged between two different tracks.

Furthermore, electrical connection elements, such as. A via or a via, respectively between the first and second flexible film substrates and, for example, at one of the connection regions to establish an electrical connection between an electrical or electronic functional element on the first film substrate and an electrical or electronic functional element on the second film substrate ,

In particular, vias become 50 between the major surfaces of a film substrate in areas where there is no connection area 32 (A ₀ areas), while vias 52 . 54 from a functional element on the first film substrate 20 to a functional element on the second film substrate 40 by means of conductive connections or plated-through holes at the connection areas 32 , z. B. by means of a conductive adhesive or a solder material can be made.

Before joining 84 the two film substrates 20 . 40 to the film pile 10 is at the connection areas, ie before or during the step of providing the film substrates 20 . 40 , applied along the linearly extending, adjacent connection areas, the bonding material.

In this case, the connection areas 34 each an elongated, coherent connection area 32 or a plurality of separate, aligned or interconnected connection regions 32 on, in which the connecting material 33 is applied. In this case, the adjacent connection areas 34 at most the dimension A ₀ and are arranged at least in the distance B ₀ . The distance or minimum distance B _{0 of} adjacent connection areas in the partial area of the flexible, multilayer circuit substrate 10 is now taking into account a partially achievable or adjustable bending radius R ₀ (target bending radius) for the flexible, multi-layer circuit substrate 10 the following condition:

Α _{0 represents} a so-called tolerance factor.

The minimum distance B ₀ with respect to the desired bending radius R ₀ and the dimension A also fulfills the following conditions: B ₀ <R _0/4 and B ₀ > A ₀ .

If in the film stack to be assembled to obtain the flexible multilayer circuit substrate 10 different target bending radii R ₀ , R _{1 to be set} for different bending requirements, can also be another connecting material 33 to a plurality of further, separately arranged connection areas 32 in another subarea 14 the first and / or the second flexible film substrate 20 . 40 be applied, wherein the further connection areas each have a further dimension A ₁ and are at least spaced at a distance B ₁ from an adjacent, further connection area. In this case, the further distance B ₁ is greater again than the further dimension A ₁ to choose. Further, the further bonding material has a further thickness D ₁ for spacing the first and second flexible film substrates 20 . 40 in the further subarea 14 on.

The other connecting material 33 becomes mm at the other connection areas 32 along linearly extending, adjacent, further connection areas 34 applied, wherein the further connection areas 34 each an elongated, coherent connection area 32 or a plurality of separate, aligned connection regions 32 exhibit. In the further subarea 14 Now the distance (minimum distance) B _{1 must} again be selected in accordance with the above condition (s).

According to the in 9b illustrated method 90 for producing a flexible, multilayer circuit substrate 10 with a for example partially reachable or adjustable bending radius (target bending radius) R ₀ is in one step 92 on a first and / or second provided flexible film substrate 20 . 40 first a connecting material 33 at least in one subarea 12 a major surface of the first and / or second flexible film substrate 20 . 40 at a plurality of symmetrically arranged and separate connection areas 34 applied. In this case, the connection areas 34 each an elongated, coherent connection area 32 or a plurality of separate connection regions aligned with each other (along a straight or curved connecting line) 32 which furthermore have at most one dimension A ₀ . The connection areas 34 So they are either coherent or partially in individual connection areas 32 divided and arranged aligned along a straight or curved connecting line to each other.

In particular, the adjacent connection areas 32 at least one distance B ₀ to each other, wherein the connecting material 33 in the connection areas 34 at the connection areas 32 has at least a thickness D ₀ to the complaint of the first and second film substrate at least in the partial area. The distance B ₀ fulfills the following condition:

Finally, the first and second flexible film substrates become 20 . 40 in one step 94 at least in the partial area by means of the connecting material at the connecting areas 32 in the connection areas 34 connected with each other.

In particular, the bonding material becomes one step 96 applied to the connection areas so that the connection areas 32 symmetrical to each other, z. In a parallel linear or orthogonal grid on the major surface of the first and / or second flexible film substrates 20 . 40 arranged after the joining of the first and / or second flexible film substrate, a preferential bending direction of the flexible multilayer film substrate 10 to get at least in the subarea.

According to the present inventive production process, the individual film substrates 20 . 40 in a roll-to-roll process to the respective processing step. Further, the respective bonding material may be on a major surface of one of the film substrates 20 . 40 or on both opposing major surfaces of both film substrates 20 . 40 to be ordered.

If as mechanical connection material 33 z. B. an adhesive material is used, this can be cured, for example, using pressure, heat and / or for example UV radiation or the final connection properties are obtained. Becomes For example, when using a solder material as a mechanical bonding material, this solder material is at least at the connecting regions on at least one or both film substrates 20 . 40 arranged, wherein liquefied in a reflow process, the solder material and after cooling z. B. is cured. When using a solder material, it should be noted that on the opposite major surfaces of the first and second semiconductor substrate 20 . 40 mutually aligned connection areas for entering into a connection with the solder material are arranged.

In the structure according to the invention of a flexible, multilayer circuit substrate 10 or the method according to the invention for producing the flexible, multilayer circuit substrate 10 the topology of the connection regions in at least two film substrates is chosen such that the mechanical connection regions 32 are separated from each other and whose spacing B ₀ , ie the minimum distance between adjacent connection regions, is greater than the dimension A _{0 of} the connection regions, depending on the desired bending radius R ₀ provided in the application, and selected for example by means of a mathematical estimation equation as a function of a desired Bend radius R ₀ and the thickness D _{0 of} the applied bonding material can be determined or relatively accurately estimated, so that the resulting flexible multilayer circuit substrate 10 in terms of its flexibility or flexibility due to a bending stress very good, adjustable properties that are optimally tuned in particular to the particular application has.

In particular, this results in a flexibility or flexibility of the resulting, flexible, multilayer circuit substrate that is significantly improved compared with the prior art 10 reached. Moreover, in a bending stress of the flexible multilayer circuit substrate of the present invention 10 , ie the layer stack of at least two film substrates or substrate planes 20 . 40 a relatively low mechanical stress due to the topology of the invention over the entire cross-section of the circuit substrate 10 and in particular on the outer surfaces of the circuit substrate 10 be achieved. These advantages due to less stress on the film stack 10 come especially into play when electrical or electronic functional elements or components in the film stack 10 be integrated, since these functional elements and their contact points to the respective interconnects are then also exposed to a significantly lower mechanical stress. Thus, for example, a mechanical breakage of interconnects, a mechanical fracture of contacts of functional elements with interconnects, or a delamination of the layer structure in the inventive concept for a flexible, multilayer film substrate can be 10 taking into account the topology according to the invention for the contact areas, taking into account an achievable target bending radius and thus substantially, any mechanical or electrical defects of the circuit substrate 10 significantly reduced due to bending stresses.

wobei erfindungsgemäß begrifflich unter dem näherungsweisen Wert eine Größenordnung des Abstandes B₀ zu verstehen ist.The topology according to the invention with regard to the connecting regions or connecting regions of a flexible, multilayer circuit substrate provided with a connecting material is now distinguished, for example, in that a first film substrate 20 is used, with at least one second film substrate 40 by means of a mechanical joining material, e.g. As an adhesive or a solder material, is connected, wherein the geometrically structured junction, ie the connection area, spaced from a neighboring geometrically structured junction and is disposed separately therefrom, wherein a geometric orientation of the connection areas, for example, perpendicular to a possible bend or a preferred bending radius for the flexible, multilayer circuit substrate 10 at least in the subarea runs. A possible embodiment of the topology according to the invention consists in the fact that the distance (minimum distance) B ₀ between adjacent connection regions is approximately predetermined, for example, by means of a mathematical description

according to the invention conceptually by the approximate value is an order of magnitude of the distance B ₀ to understand.

Tolerance factor α ₀ allows the equation or condition to incorporate a certain tolerance with respect to the strictly mathematical geometry in order, for example, to take into account manufacturing tolerances, different material properties of film substrates, etc.

Although some aspects have been described in the context of a device, it will be understood that these aspects also constitute a description of the corresponding method, so that an element of a device or its configuration is also to be understood as a corresponding method step or as a feature of a method step. Similarly, aspects described in connection with or as a method step also represent a description of a corresponding item, detail or feature of a corresponding apparatus.

Claims (32)

Flexible, Multilayer Circuit Substrate ( 10 ), comprising: a first and a second flexible film substrate ( 20 . 40 ), wherein at least a portion of the opposing major surfaces of the first and second film substrates are bonded by means of a bonding material to a plurality of separately arranged connection regions (FIG. 32 ), wherein the connection areas have a maximum dimension A ₀ and at least with a distance B ₀ are spaced from an adjacent connection area, wherein the distance B _{0 is} greater than the dimension A ₀ , and wherein the bonding material at the connection areas ( 32 ) at least one thickness D ₀ for spacing the first and second flexible film substrates ( 20 . 40 ) having. A circuit substrate according to claim 1, wherein the connection regions ( 32 ) are arranged with the bonding material symmetrical to each other, in a linear orientation or in an orthogonal raster to form a preferential bending direction of the flexible multilayer circuit substrate ( 10 ) in the subarea ( 12 ) to obtain. Circuit substrate according to claim 1 or 2, wherein the connection regions ( 32 ) have a circular, oval or rectangular basic shape. Circuit substrate according to one of claims 1 to 3, wherein the connecting material ( 33 ) comprises an adhesive material or a solder material. Circuit substrate according to one of claims 1 to 4, wherein on the first and / or second film substrate ( 20 . 40 ) is arranged schichtfömig trained, electrical or electronic functional element. A circuit substrate according to any one of claims 1 to 5, wherein an electrical connection element between a first and second main surface of the first flexible film substrate (FIG. 20 ) outside the area of the connection areas ( 32 ) is arranged to provide an electrical connection between a functional element on the first main surface and a functional element on the second main surface of the first film substrate ( 20 ). A circuit substrate according to any one of claims 1 to 5, wherein an electrical connection element between the first and second flexible film substrates at one of the connection regions ( 32 ) is arranged to provide an electrical connection between a functional element on the first film substrate ( 20 ) and a functional element on the second film substrate ( 40 ). The circuit substrate of claim 7, wherein the electrical connection element is at the connection area 32 a conductive adhesive or a conductive solder material. Circuit substrate according to one of claims 1 to 8, wherein the connecting material ( 33 ) at the connection areas ( 32 ) of the adjacent connection areas ( 34 ), and wherein the connection areas ( 34 ) an elongated connection area ( 32 ) or a plurality of separate connection areas ( 32 ) exhibit. A circuit substrate according to claim 9, wherein the adjacent connection areas ( 34 ) have the dimension A ₀ and are arranged at least in the distance B ₀ , and wherein the distance B _{0 of} adjacent connection areas ( 34 ) taking into account a desired bending radius R ₀ for the subregion ( 12 ) of the flexible multilayer circuit substrate ( 10 ) satisfies the following condition:

The circuit substrate according to claim 10, wherein the distance B ₀ with respect to the target bending radius R ₀ and the dimension A ₀ further satisfies the following conditions: B ₀ <R _0/4 and B ₀ > A ₀ . Circuit substrate according to one of claims 1 to 11, wherein in a further subregion ( 14 ) of the first and / or the second flexible film substrate ( 20 . 40 ), a further connection material at a plurality of further connection areas, which are arranged separately, is applied, wherein the connection areas have a dimension A ₁ and at least with a distance B ₁ are spaced from an adjacent, further connection area, wherein the distance B ₁ greater is the dimension A ₁ , and wherein the further bonding material has a thickness D ₁ for spacing the first and second flexible film substrates (FIG. 20 . 40 ) in the further subarea. The circuit substrate according to claim 12, wherein the further bonding material is applied to the further bonding regions along further, adjacent bonding regions, and wherein the further bonding regions are each an elongate, further bonding region or a connection region Have a plurality of separate, further connection areas. Circuit substrate according to claim 12 or 13, wherein the further, adjacent, connecting regions have the dimension A ₁ and are arranged at least in the distance B ₁ , the distance B ₁ taking into account a desired bending radius R ₁ in the further subregion ( 14 ) of the flexible multilayer circuit substrate ( 10 ) satisfies the following condition:

The circuit substrate according to claim 14, wherein the distance B ₁ with respect to the target bending radius R ₁ and the dimension A ₁ further satisfies the following conditions: B ₁ <R _1/4 and B _{1> A1.} Flexible, multilayer circuit substrate having a predetermined desired bending radius R ₀ , comprising: a first and a second flexible film substrate ( 20 . 40 ), which at least in one subarea ( 12 ) of the opposing major surfaces of the first and second film substrates ( 20 . 40 ) with a connecting material ( 33 ) at a plurality of symmetrically arranged and separated connection areas ( 32 ) are mechanically connected, wherein the connection areas form an elongated, coherent connection area ( 32 ) or a plurality of separate, mutually aligned connection areas ( 32 ), and further have a maximum dimension A ₀ , wherein the adjacent connection areas ( 34 ) have at least one distance B ₀ to each other, wherein the connecting material ( 33 ) in the connection areas ( 34 ) at least one thickness D ₀ for spacing the first and second flexible film substrates ( 20 . 40 ), and wherein the distance B ₀ satisfies the following condition:

A circuit substrate according to claim 16, wherein said connection regions ( 32 ) with the connecting material ( 32 ) symmetrical to one another, in a linear orientation or in an orthogonal grid on the main surface of the first and / or the second flexible film substrate ( 20 . 40 ) are arranged to provide a preferential bending direction of the flexible multilayer circuit substrate ( 10 ) in the subarea ( 12 ). Circuit substrate according to one of claims 16 or 17, wherein the connecting material ( 33 ) comprises an adhesive material or a solder material. Procedure ( 80 ) for producing a flexible, multilayer circuit substrate ( 10 ), with the following steps: Deploy ( 82 ) of a first and a second flexible film substrate ( 20 . 40 ), whereby at least one subregion ( 12 ) of a main surface of the first and / or the second flexible film substrate ( 20 . 40 ) at a plurality of separately arranged connection areas ( 32 ) has a connection material, wherein the connection areas ( 32 ) have a maximum dimension A ₀ and at least with a distance B ₀ are spaced from an adjacent connection area, wherein the distance B _{0 is} greater than the dimension A ₀ , and wherein the bonding material at the connection areas at least a thickness D ₀ for spacing the first and second film substrate ( 20 . 40 ), and connect ( 84 ) of the first and second flexible film substrates ( 20 . 40 ) at least in the subarea ( 12 ) by means of the bonding material at the separate connection areas ( 32 ). The method of claim 19, further comprising the step of: applying ( 86 ) of the connection material at the connection regions, the connection regions being symmetrical to one another on the main surface of the first and / or the second flexible film substrate ( 20 . 40 ) to connect after connecting ( 84 ) of the first and second flexible film substrates ( 20 . 40 ) a preferential bending direction of the flexible multilayer circuit substrate ( 10 ) in the subarea ( 12 ) to obtain. Method according to one of claims 19 or 20, further comprising the following step: application of adhesive material or solder material as connecting material ( 33 ) at the connection areas ( 32 ) on the main surface of the first and / or the second flexible film substrate ( 20 . 40 ). Method according to one of claims 19 to 21, further comprising the following step: application of a layer-formed, electrical or electronic functional element ( 60 ) on the first and / or second film substrate ( 20 . 40 ). The method of any one of claims 19 to 22, further comprising the step of: disposing an electrical via element between the two major surfaces of the first and second film substrates (12); 20 . 40 ), in an area outside the connection areas ( 32 ) in order to establish an electrical connection between a functional element on the first main surface and a further functional element on the second main surface of the first film substrate (US Pat. 20 ). The method of any one of claims 19 to 23, further comprising the step of: disposing an electrical connection element between the first and second flexible film substrates (10). 20 . 40 ) at one of the connection areas ( 32 ) in order to establish an electrical connection between a functional element on the first film substrate ( 20 ) and a functional element on the second film substrate ( 40 ). The method of any one of claims 19 to 24, further comprising the step of: applying the bonding material to the joining regions ( 32 ) along adjacent connecting regions extending along a straight or curved connecting line ( 34 ), wherein the connection areas ( 34 ) each an elongated, interconnected connection area ( 32 ) or a plurality of separately arranged, mutually aligned connection areas ( 32 ) exhibit. The method of claim 25, wherein the adjacent connection areas ( 34 ) at most have the dimension A ₀ and at least in the distance B ₀ are arranged spaced from each other, and wherein the distance B ₀ , taking into account a desired bending radius R ₀ for the subregion ( 12 ) of the flexible multilayer circuit substrate ( 10 ) satisfies the following condition:

The method of claim 26, wherein the distance B ₀ with respect to the desired bending radius R ₀ and the dimension A ₀ further satisfies the following conditions: B ₀ <R _0/4 and B ₀ > A ₀ . Method according to one of the preceding claims, further comprising the following step: applying a further bonding material to a plurality of further, separately arranged connecting regions in a further subregion ( 14 ) of the first and / or the second flexible film substrate ( 20 . 40 ), wherein the further connection regions each have a dimension A ₁ and are spaced at least a distance B ₁ from an adjacent, further connection region, wherein the distance B _{1 is} greater than the dimension A ₁ , and wherein the further bonding material has a thickness D ₁ for spacing the first and second flexible film substrates ( 20 . 40 ) in the further subarea ( 14 ) having. The method of claim 28, further comprising the step of: Applying the further bonding material to the further connecting regions of adjacent connecting regions extending along a straight or curved connecting line, wherein the further connecting regions each have a further, elongate, contiguous connecting region or a plurality of further, separate, mutually aligned connecting regions. The method of claim 28 or 29, wherein the further, adjacent connecting portions have the dimension A ₁ and are arranged at least in the distance B ₁ , and wherein the distance B ₁ , taking into account a desired bending radius R _{1 of} the flexible multilayer circuit substrate satisfies the following condition :

The method of claim 30, wherein the distance B ₁ with respect to the desired bending radius R ₁ and the dimension A ₁ further satisfies the following conditions: B ₁ <R _1/4 and B _{1> A1.} Procedure ( 90 ) for producing a flexible, multilayer circuit substrate having a desired bending radius R ₀ , comprising the following steps: application ( 92 ) of a bonding material at least in a partial area of a main surface of a first and / or a second flexible film substrate ( 20 . 40 ) at a plurality of symmetrically arranged and separated connection areas ( 32 ), wherein the connection areas ( 32 ) an elongated, coherent connection area ( 32 ) or a plurality of separate, mutually aligned connection areas ( 32 ), and further at most have a dimension A ₀ , wherein the adjacent. Connection areas ( 34 ) have at least one distance B ₀ to each other, wherein the bonding material in the connecting regions ( 34 ) at least one thickness D ₀ for spacing the first and second flexible film substrates at least in the partial area ( 12 ), wherein the distance B ₀ satisfies the following condition:

Connect ( 94 ) of the first and second flexible film substrates ( 20 . 40 ) at least in the subarea ( 12 ) by means of the bonding material at the connection areas ( 32 ).

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